U.S. Pat. No. 3,785,505 discloses a side stowable jib for crane booms in which spaced front and rear mounting brackets for the stowed jib are provided on one side of a telescoping boom base section. Another mount for the boom jib or extension is provided on the nose assembly of the boom fly section. The jib, when being swung around from its use position to its side stowed position, rotates on a releasable pivotal connection with the nose assembly and following engagement of the jib with the forward mounting bracket and the placement of jib retainer pins in such bracket, the nose assembly pivotal connection is released to permit final swinging of the jib into supportive engagement with the rear mounting bracket.
A major objective of this invention is to improve on the safety of this prior art arrangement. An unsafe situation can develop with the arrangement in the aforementioned patent if the nose assembly pivot for the jib should be disconnected before locking pins are placed in the front mounting bracket. In such a case, the jib could slip and fall from the front mounting bracket while it is being brought into engagement with the rear mounting bracket on the adjacent side of the boom.
The present invention completely eliminates this unsafe possibility through provision on the forward mounting bracket or assembly of a biased latch which is always engaged and operated by contact with the jib when the latter first swings into engagement with the forward mounting assembly. When the nose assembly pivot is disconnected immediately following such engagement, the safety latch assures that the jib is safely supported during the final transitional movement into supportive engagement with its rear mounting assembly on the boom. In the reverse situation, when the jib is being swung around from its side stowed position to its extended use position, it is always safely held in the forward mounting assembly until the pivotal connection with the nose assembly of the boom is re-established, including during the critical transition period between the release of the jib from the rear mounting assembly and its reconnection with the nose assembly.
After the safe reconnection of the base of the jib with the nose assembly, the biased safety latch of the first mounting assembly is released by operation of a release lever on the first mounting assembly which can be reached from ground level.
Other meritorious features of the present invention will appear to those skilled in the art during the course of the following description.